Hello,
The minimum value allowed by the left property is 1. It you set 0, phpdocx sets the default value.
About line breaks, they are only added when the content is a block type or there's some line break. We recommend you to check the HTML you are adding, and use display inline or float left properties if needed. The replaceVariableByHTML method also includes the type option that allows to do block or inline replacements, that can be useful for some placeholders.
Regards.